CH639764A5 - METHOD FOR ADJUSTING A GIVEN BIAS IN A THREAD IN A tester, ESPECIALLY A REISSFESTIGKEITSPRUEFGERAET. - Google Patents

Description

639 764 2

PATENT REQUIREMENTS difficult to define braking force, and a change

1. The procedure for setting a given pre-tensioner is difficult to reach; Under certain circumstances on a thread in a test device, in particular one of the auxiliary devices must be used to determine the real tear strength tester with a thread insertion mechanism thread tension. Deflection eyes and the like. such mus and thread clamps for holding the thread, of which s auxiliary devices can falsify the measurement result, one is connected to a force measuring device, thereby yarn scales also represent quite complex and complicated that the thread (3) initially in the thread-decorated mechanisms which are permanently or periodically clamped (5, 7) and require maintenance after closing.

Thread clamp connected to the force measuring device (6) The present invention avoids these disadvantages and (5) by means of the force measuring device (6) the initial tension relates to a method for setting a given condition (VI) measured and with a predetermined condition Tension on a thread in a test device, in particular a value representing tension (V2), is compared, whereupon a tensile strength tester, which is further tensioned or relaxed by the other thread (3), until the method steps specified in claim 1 are distinguished. Initial tension (VI) of the thread (3) of the pretension (V2) The consideration is in accordance with the method according to the invention. 15 is based on the fact that a force measuring device such as that used in

2. The method according to claim 1, characterized in that strength testing devices are used, a precision measuring device that advises the further tension or relaxation of the thread (3). This should not only serve for the determination of the tension after closing the thread clamps (5, 7) by a relative load alone, but should also achieve the pre-tensioning movement of the thread clamps (5, 7). with the same accuracy at the start of the test

3. The method according to claim 1, characterized in 20 define. In this way, all frictional influences resulting from the further tension of the thread (3) after the thread guiding members have closed are kept away from the effectively measured clamp (5) connected to the force measuring device (6).

due to the further movement of the transport clamp (4) with the opened - Because of the diversity of the lower thread clamp (7) under the pretensioner and when the expansion already occurs, it is not possible to ensure equality between the given pretension (V2) and the tension to compensate for the lower thread clamp (7) already closed by a corresponding shortening of the catching tension (V1).

and the transport clamp (4) are opened. Based on the description and the figures,

5. The method according to claim 1, characterized in examples of management of the invention explained. This shows that the given pretension (V2) as an electrical threshold 1 schematically shows a tensile strength tester with a

len value (22) is shown, when reaching the 30 measuring means,

value (23) is moved to a starting position (0). Figures 2 and 3 each a load diagram for one

6. The method according to claim 5, characterized in thread,

that the electrical threshold (22) is set. FIG. 4 schematically shows a variant of the thread insertion

7. The method according to claim 2, characterized in running.

that the measured value (24) is corrected by a factor that is 35 In a the ratio between the original clamping length tester, indicated by its outline 1 in FIG. 1, the thread 3 to be tested becomes (E0) and that one until the given pretension is reached Bobbin 2 is pulled off, guided over deflection eyelets 11, 12 and (V2) corresponds to the thread length (E ,, E /) that has occurred. into the actual test section between a measuring terminal 5

and a tension clamp 7 inserted.

40 The deflecting eyelets 11, 12 serve both to guide the thread and to provide a certain amount of thread insulation which serves to ensure that the invention relates to a method for adjusting one of the threads, which is stretched, is introduced into the test section and avoids the pretensioning of a thread in a testing device, for example curling becomes. For this in particular a tear strength tester. Purpose the device contains an insertion mechanism, the one

Test method on automatic tear strength test 45 transport clamp 4, which are largely standardized on a suitable entry, i.e. The initial conditions 9 circulates, the thread piece is detected at A, for example, and the conditions under which a test is carried out are directed via the deflection eyelet 12 between the measuring clamp 5 or, according to recognized regulations, in order to place the same tension clamp 7 for all tests and that Thread at B releases again. To create conditions. In addition to the clamping length, as the deflecting eyelets 11, 12 only exert a small braking effect on the forming speed, moisture and temperature of the thread 3, it is generally only used with a small surrounding atmosphere, among other things. the pretension, the initial tension V1 (which should be smaller than the selected pretension thread at the start of the test, should be set to V2) is also placed between the terminals 5, 7. It is also conceivable that the force-elongation values strongly depend on this preload - e.g. if the thread 3 depends on the take-off. In addition, the thread should be caught in the stretched state by the bobbin 2 - that the initial tension V can be tensioned when. 55 insertion is already greater than the prescribed preload

Tear resistance testers of known design produce bung V2. In this case, the tension clamp 7 must first be approached, for example, to a certain pretension of the inserted Fa measuring clamp 5 until the correct pretensioning is achieved by a calibrated thread brake via which the thread tension V2 is reached, whereupon the actual tension between the supply spool and the transport clamp that can be used.

laying mechanism is guided. By appropriate setting eo The bobbin designated by 2 can also be replaced by a suitable braking force of the thread brake, the thread is replaced under the type of a bobbin magazine, from the voltage of this voltage into the test terminals. After closing the pieces in a certain number of several coils, the stretching process begins with this pretension. can be taken. However, this has to do with the

Other embodiments have no influence on the method to be used.

a thread scales, with which the thread 65- The test device is advantageously designed so that the desired pretension is given. Measuring clamp 5 with an essentially stationary force

However, these known arrangements have a different diameter 6, while the tension clamp 7 has one of its disadvantages. Thread brakes practice a path 8 on the thread which is displaceable and the stretching of the thread 3

testifies. The tensile stress values recorded by the dynamometer 6 are processed in an evaluation device 10.

A cycle of a tensile strength test now proceeds such that after the measuring clamp 5 and tension clamp 7 are closed, the latter is moved downward, as a result of which the tension P in the clamped thread piece C from the original one at V | lying value increases.

This behavior is shown graphically in FIG. 2.

Along the abscissa 20 is the path 5 of the tension clamp 7, on the ordinate 21 the tensile force or thread tension P is drawn. With a given bias voltage V2 is designated. Starting from the value P = V, for S = o, this thread tension P initially increases at least approximately linearly with increasing path S according to curve 23. When the value V2 is reached - the point of intersection with the size 22 of the preload - this is now used in the evaluation device as a threshold value for the measurement of the tensile force acting on the dynamometer 6 serving as the starting position 0 for the further increase in the tensile force.

If the dynamometer 6 already sets a thread tension V | at the start of the test fixed, which is higher than the pretension V2, the tension clamp 7 must first be moved against the measuring clamp 5 until the pretension V2 is reached or undercut (FIG. 3). The tension clamp 7 can then be moved again in the direction of increasing thread tension P and from the passage of the tension by the value of the pre-tension V? the normal tearing force measurement is carried out in accordance with the force-elongation diagram 24.

This method has the following advantages over the known mechanical devices:

- the preload setting is more accurate and faster;

- it does not require any additional mechanical devices;

- The preload values to be set can be reproduced at any time;

- Any bias value can be selected that is within the measuring range of the force measuring device.

3,639,764

As a result of the stretch which the loose thread 3, which is loosely tensioned with a low pretension or higher pretension than V2, suffers between the measuring clamp 5 and the tension clamp 7 until the pretension V2 is reached, the actual test length is somewhat changed. The clamping length E) measured when the preload V2 is reached must therefore be used as the basis for the strain measurement. This can be done by a correction that is carried out in the evaluation device 10. For this purpose, the measured strains S must be corrected with a factor that expresses the ratio of the specified clamping length E0 to the length E] of the pre-tensioned thread. FIG. 2 shows a force-elongation diagram corrected in this way at 25. In FIG. 3, 25 'denotes the corrected force-elongation diagram in the event that the thread was inserted with an excessively high initial tension V] and therefore had to be shortened to the clamping length E / first.

With the method according to the invention, an advantageous variant of the insertion process according to FIG. 4 can also be used. The transport clamp 4 detects the thread 3 at A, for example, and places it along the path 9 between the thread clamps 5, 7. Arrived at F], the thread clamp 5 closes first. During the distance 25 pieces F | -F2 of the transport clamp 4, the thread piece 3 'is relaxed, since the stretched length clamp 7-F2 is somewhat shorter than that clamp 7 to F]. As the feed clamp 4 advances towards F3, additional thread length is required again, but this (since thread clamp 5 is closed 3o) is only available by stretching and thus increasing the thread tension. The force measuring device 6 indicates this thread tension and triggers a closing command for the thread clamp 7 via the evaluation device 10 as soon as the given pretension V2 is reached. Thus, the thread piece 3 '35 is held in the test section C under this pretension. The further test procedure consists in the known increase in thread tension by increasing the distance between the clamps while continuously monitoring the load on the force measuring device.

C.

2 sheets of drawings